Communication between data processing devices can currently be done in accordance with one of a variety of interface standards such as RS-232, RS-422, RS-423, RS-449, RS-485, V.35, MIL-188-114A, and EIA-530. Each of these interface standards defines a particular protocol for exchange of control signals between the device, and specific signal levels and waveforms. Each of these interface standards was developed to address unique requirements in specific applications or wide areas of data communications. Due to the large number of interface standards in use at the present time, compatibility between data processing equipment modules is not always possible, or can only be done through the use of cumbersome intermediary adaptor units.
Data processors are often used in association with a variety of communication networks. The physical interface to be used to connect to a particular network is dependent upon the application, the nature of available interconnection equipment, the data rate etc., and often varies from one application to the next. This presents to the users, two different problems. First, is the need to easily determine the interface standard of the other devices in the network. Secondly, the users must find a way to adapt his machine to that standard. Ideally, this adaptation should be accomplished without having to resort to the rewiring of interface or the setting of jumper connections or switches, and other procedures prone to human errors.
The current solutions either offer a limited versatility, or are very costly, cumbersome and tedious to implement. Some data processors are provided with an hybrid serial port which can accommodate two different interface standards such as RS-232 and subset of RS-422 or RS-423. Some serial ports offer multiple interface which can be implemented by the rewiring of jumpers on an input/output control board. Some users resort to the use of external converter boxes dedicated to the translation of signals between devices using two specific interface standards. A separate and different converter box must be used when interfacing with another device using a different interface standard.
U.S. Pat. No. 4,972,470, Farago suggests a more flexible solution to multiple standard interfacing problems by offering a interface module that can be programmed by the host computer to assume one of a variety of interface standard configurations. While this approach may simplify the resolution of the second problem, i.e. reconfiguration of the interface, it does not relieve the user from the often difficult task of determining in which type of interface standard his machine must be reconfigured, then, once this has been determined, of triggering the interface reconfiguration process. It would be more advantageous and far more practical to have an input/output port that can adapt itself to a variety of communication protocols without requiring operator intervention.